Food additive carrageenan: Part I: A critical review of carrageenanin vitrostudies, potential pitfalls, and implications for human health and safety

Methylation-GC-MS/FID-Based Glycosidic Linkage Analysis of Unfractionated Polysaccharides in Red Seaweeds

Glycosidic linkage analysis was conducted on the unfractionated polysaccharides in alcohol-insoluble residues (AIRs) prepared from six red seaweeds (Gracilariopsis sp., Prionitis sp., Mastocarpus papillatus, Callophyllis sp., Mazzaella splendens, and Palmaria palmata) using GC-MS/FID analysis of partially methylated alditol acetates (PMAAs). The cell walls of P. palmata primarily contained mixed-linkage xylans and small amounts of sulfated galactans and cellulose. In contrast, the unfractionated polysaccharides of the other five species were rich in galactans displaying diverse 3,6-anhydro-galactose and galactose linkages with varied sulfation patterns. Different levels of cellulose were also observed. This glycosidic linkage method offers advantages for cellulose analysis over traditional monosaccharide analysis that is known for underrepresenting glucose in crystalline cellulose. Relative linkage compositions calculated from GC-MS and GC-FID measurements showed that anhydro sugar linkages generated more responses in the latter detection method. This improved linkage workflow presents a useful tool for studying polysaccharide structural variations across red seaweed species. Furthermore, for the first time, relative linkage compositions from GC-MS and GC-FID measurements, along with normalized FID and total ion current (TIC) chromatograms without peak assignments, were analyzed using principal component analysis (PCA) as a proof-of-concept demonstration of the technique's potential to differentiate various red seaweed species.

Evidence and hypotheses on adverse effects of the food additives carrageenan (E 407)/processed Eucheuma seaweed (E 407a) and carboxymethylcellulose (E 466) on the intestines: a scoping review

This scoping review provides an overview of publications reporting adverse effects on the intestines of the food additives carrageenan (CGN) (E 407)/processed Eucheuma seaweed (PES) (E 407a) and carboxymethylcellulose (CMC) (E 466). It includes evidence from human, experimental mammal and in vitro research publications, and other evidence. The databases Medline, Embase, Scopus, Web of Science Core Collection, Cochrane Database of Systematic Reviews and Epistemonikos were searched without time limits, in addition to grey literature. The publications retrieved were screened against predefined criteria. From two literature searches, 2572 records were screened, of which 224 records were included, as well as 38 records from grey literature, making a total of 262 included publications, 196 on CGN and 101 on CMC. These publications were coded and analyzed in Eppi-Reviewer and data gaps presented in interactive maps. For CGN, five, 69 and 33 research publications on humans, experimental mammals and in vitro experiments were found, further separated as degraded or native (non-degraded) CGN. For CMC, three human, 20 animal and 14 in vitro research publications were obtained. The most studied adverse effects on the intestines were for both additives inflammation, the gut microbiome, including fermentation, intestinal permeability, and cancer and metabolic effects, and immune effects for CGN. Further studies should focus on native CGN, in the form and molecular weight used as food additive. For both additives, randomized controlled trials of sufficient power and with realistic dietary exposure levels of single additives, performed in persons of all ages, including potentially vulnerable groups, are needed.

Carrageenan in meat: improvement in lipid metabolism due to Sirtuin1-mediated fatty acid oxidation and inhibited lipid bioavailability

Kappa-carrageenan (κ-CGN) is widely used in the meat industry. However, its impact on the host metabolism is less revealed. The current study investigated the effect of κ-CGN in pork-based diets on the lipid metabolism of male C57BL/6J mice. The κ-CGN supplement significantly suppressed the increase in body weight by 6.79 g on an average. Supplement of κ-CGN in high-fat diets significantly upregulated the genes and protein expression of Sirtuin1, which was accompanied by the increased gene expression of downstream fatty acids oxidation (Cpt1a and Acadl). The sirtuin1-mediated improvement of lipid metabolism was negatively associated with the levels of bile acids, especially for deoxycholic acid, 3β-cholic acid, glycodeoxycholic acid and glycolithocholic acid. Moreover, κ-CGN in high-fat diets inhibited lipid digestion and absorption, being associated with the decrease in lipid accumulation and improved serum lipid profile. These results highlighted the role of κ-CGN in alleviating diet-induced adiposity by promoting energy expenditure and suppressing the bioavailability of ingested lipids.

Biochemical Characteristics and Potential Biomedical Applications of Hydrolyzed Carrageenans

Seaweed contains a variety of bioactive compounds; the most abundant of them are polysaccharides, which have significant biological and chemical importance. Although algal polysaccharides, especially the sulfated polysaccharides, have great potential in the pharmaceutical, medical and cosmeceutical sectors, the large molecular size often limits their industrial applications. The current study aims to determine the bioactivities of degraded red algal polysaccharides by several in vitro experiments. The molecular weight was determined by size-exclusion chromatography (SEC), and the structure was confirmed by FTIR and NMR. In comparison to the original furcellaran, the furcellaran with lower molecular weight had higher OH scavenging activities. The reduction in molecular weight of the sulfated polysaccharides resulted in a significant decrease in anticoagulant activities. Tyrosinase inhibition improved 2.5 times for hydrolyzed furcellaran. The alamarBlue assay was used to determine the effects of different Mw of furcellaran, κ-carrageenan and ι-carrageenan on the cell viability of RAW264.7, HDF and HaCaT cell lines. It was found that hydrolyzed κ-carrageenan and ι-carrageenan enhanced cell proliferation and improved wound healing, whereas hydrolyzed furcellaran did not affect cell proliferation in any of the cell lines. Nitric oxide (NO) production decreased sequentially as the Mw of the polysaccharides decreased, which indicates that hydrolyzed κ-Carrageenan, ι-carrageenan and furcellaran have the potential to treat inflammatory disease. These findings suggested that the bioactivities of polysaccharides were highly dependent on their Mw, and the hydrolyzed carrageenans could be used in new drug development as well as cosmeceutical applications.

How does carrageenan cause colitis? A review

Carrageenan is a common additive, but mounting studies have reported that it may cause or aggravate inflammation in the intestines. The safety of carrageenan remains controversial and its inflammatory mechanisms are unclear. In this review, the pathogenesis of colitis by carrageenans was discussed. We analyzed the pathogenesis of inflammatory bowel disease, followed that line of thought, the existing evidence of carrageenans causing colitis in cellular and animal models was summarized to draw its colitis pathogenesis. Two pathways were described including: 1) carrageenan changed the composition of intestinal microbiota, especially Akkermansia muciniphila, which destroyed the mucosal barrier and triggered the inflammatory immune response; and 2) carrageenan directly contacted with receptors on epithelial cells and activated the NF-κB inflammatory pathway. This review aim to provide guidance for exploring the treatment of colitis caused by carrageenan, and safe processing and utilization of carrageenan in food industry, which is worthy of study in the future.

In Vitro Toxicity Evaluation of Carrageenan on Cells and Tissues of the Oral Cavity

Carrageenan is a highly potent anti-human papillomavirus (HPV) agent with the potential for formulation as a mouthwash against oral HPV infection. However, its toxic effect on tissues of the oral cavity is currently unknown. This study aims to evaluate the safety of carrageenan on human cells and tissues of the oral cavity. Human salivary gland cells and reconstructed human oral epithelium (RHOE) were used for this in vitro study. The cells were subjected to 0.005–100 µg/mL of carrageenan for 4, 12, and 24 h in quadruplicate. RHOE were exposed to 100 µg/mL of carrageenan for 24 h in triplicate and stained with hematoxylin/eosin for histological analyses. All experiments had saline and 1% sodium dodecyl sulphate (SDS) as negative and positive controls, respectively. Carrageenan tissue toxicity was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to quantify cell viability. Tissue toxicity was further evaluated histologically by an oral pathologist to assess morphological changes. Our data showed that carrageenan did not significantly decrease cell and tissue viability when compared to the positive control. The histological evaluation of the RHOE also showed no loss of viability of the carrageenan-treated sample compared to untreated tissue. In contrast, 1% SDS-treated RHOE showed extensive tissue destruction. Our experiments suggest that carrageenan is safe for use in the oral cavity.

In vitro effects of λ-carrageenin in the head-kidney leucocytes of gilthead seabream (Sparus aurata)

The λ-carrageenin is a sulphated mucopolysaccharide that has been used for decades to induce experimental inflammation in mammals. However, it has been little considered in fish. We studied the in vitro effects of λ-carrageenin on gilthead seabream (Sparus aurata L.) head-kidney leucocytes (HKLs). For this purpose, HKLs were incubated with serial concentrations (from 0 to 1,000 μg mL-1) of λ-carrageenin for 3, 6, 12 and 24 h to assess its influence on cell viability and morphology, cell activity and modulation of several selected inflammation-related genes. The viability results demonstrated that λ-carrageenin has no negative effects on HKLs. The respiratory burst activity and phagocytic ability of HKLs after being incubated with λ-carrageenin (100 and 1,000 μg mL^-1) for 24 h were increased, whereas the phagocytic capacity was inhibited by the higher dose at the same experimental time compared with control samples. However, the peroxidase activity of HKLs was not changed by incubation with λ-carrageenin. According to transmission electron microscopy results, incubation of HKLs with the higher dose of λ-carrageenin appeared to activate the cells being evident different morphological changes without sign of cell death. Furthermore, up-regulation of three proinflammatory cytokines (il1b, tnfa, and il6) and down-regulation of anti-inflammatory genes (tgfb) were denoted in HKLs incubated with carrageenin. The present results provide a detailed approach to the effects of λ-carrageenin on fish leucocytes, which could have some impact on how we understand the response of these cells when inducing an inflammatory process in fish.

The risk of carrageenan-induced colitis is exacerbated under high-sucrose/high-salt diet

As a common used food additive, the threat of carrageenan to colon health is controversial, and is inseparable from personal eating habits. However, no detailed descriptions are available concerning the influence of different dietary patterns on the risk of carrageenan-induced colitis. In this study, we explored the risk of κ-carrageenan-induced colitis under high-sucrose or high-salt diet in mice. Intervention with carrageenan under high-sucrose diet significantly reduced colon length and induced more serious deepening of the crypts. In addition, the intake of carrageenan under high-sucrose/high-salt diet induced more serious goblet cell reduction and increased intestinal permeability. 16S rRNA sequencing and LC-MS based metabonomic approaches were conducted to explore the changes of gut microbiota and metabolites. It was found that the intake of carrageenan under high-sucrose/high-salt diet significantly reduced the abundance of anti-inflammatory bacterium and increased the abundance of harmful bacterium, which was significantly related to the decrease of anti-inflammatory metabolites in colon, such as methyl caffeate, spermine, oleanolic acid and senecionine. Overall, high-sucrose or high-salt diet increased the risk of carrageenan-induced colitis. This reminds us to maintain good eating habits, do not prefer high-sugar or high-salt foods, and try not to consume large amounts of carrageenan continuously to maintain gut health.

Advancement of biorefinery-derived platform chemicals from macroalgae: a perspective for bioethanol and lactic acid

The extensive growth of energy and plastic demand has raised concerns over the depletion of fossil fuels. Moreover, the environmental conundrums worldwide integrated with global warming and improper plastic waste management have led to the development of sustainable and environmentally friendly biofuel (bioethanol) and biopolymer (lactic acid, LA) derived from biomass for fossil fuels replacement and biodegradable plastic production, respectively. However, the high production cost of bioethanol and LA had limited its industrial-scale production. This paper has comprehensively reviewed the potential and development of third-generation feedstock for bioethanol and LA production, including significant technological barriers to be overcome for potential commercialization purposes. Then, an insight into the state-of-the-art hydrolysis and fermentation technologies using macroalgae as feedstock is also deliberated in detail. Lastly, the sustainability aspect and perspective of macroalgae biomass are evaluated economically and environmentally using a developed cascading system associated with techno-economic analysis and life cycle assessment, which represent the highlights of this review paper. Furthermore, this review provides a conceivable picture of macroalgae-based bioethanol and lactic acid biorefinery and future research directions that can be served as an important guideline for scientists, policymakers, and industrial players.

Graphical abstract

Algal polysaccharides and derivatives as potential therapeutics for obesity and related metabolic diseases

The potential and challenges of algal polysaccharides and their derivatives as potential therapeutic agents for obesity and its related metabolic diseases.

Bioactive polysaccharides from red seaweed as potent food supplements: a systematic review of their extraction, purification, and biological activities

Most marine macroalgae such as red seaweeds are potential alternative sources of useful bioactive compounds. Beside serving as food source, recent studies have shown that red seaweeds are rich sources of bioactive polysaccharides. Red seaweed polysaccharides (RSPs) have various physiological and biological activities, which allow them to be used as immunomodulators, anti-obesity agents, and prebiotic ingredients. Lack of summary information and human clinical trials on the various polysaccharides from red seaweeds, however limits industrial-scale utilization of RSPs in functional foods. This review summarizes recent information on the approaches used for RSPs extraction and purification, mechanistic investigations of their biological activities, and related molecular principles behind their purported ability to prevent diseases. The information here also provides a theoretical foundation for further research into the structure and mechanism of action of RSPs and their potential applications in functional foods.

The mechanism exploration of the non-colonic toxicity and obesity inhibition of food-grade κ-carrageenan by transcriptome

Previous study has suggested the colonic nontoxicity and obesity inhibition of food-grade κ-carrageenan in obese mice. Further study using transcriptome is important to provide further understanding on the gene expressions of inflammation and obesity. Here, the obese mice without any treatment (HFD) or with 5% food-grade κ-carrageenan diet intervention (H5%) were used to perform colonic transcriptome sequencing. The results showed that genes involved in the inflammatory pathways or tight junction protein encoding were not significantly dysregulated by 5% carrageenan. However, the expression of lipid metabolism genes meaningfully changed as evidenced by the decreased gene levels of adipocytokines, lipogenesis, lipid absorption and transport, and the increased adipolysis and oxidation. In addition, the carrageenan metabolism experiments by toluidine blue (TB) staining of colon and high-performance size exclusion chromatography (HPSEC) of feces supernatant showed that the food-grade κ-carrageenan was not absorbed or significantly degraded in the digestive tract of obese mice. Hence, the fact that food-grade κ-carrageenan was not significantly metabolized by the organism and did not cause obvious dysregulation of colonic inflammatory genes provided evidences for its noncolonic toxicity in obese mice. An anti-obesity potential of food-grade κ-carrageenan was probably mediated by the regulation of lipids metabolism-related genes.

A review: Gelatine as a bioadhesive material for medical and pharmaceutical applications

Bioadhesive polymers offer versatility to medical and pharmaceutical inventions. The incorporation of such materials to conventional dosage forms or medical devices may confer or improve the adhesivity of the bioadhesive systems, subsequently prolonging their residence time at the site of absorption or action and providing sustained release of actives with improved bioavailability and therapeutic outcomes. For decades, much focus has been put on scientific works to replace synthetic polymers with biopolymers with desirable functional properties. Gelatine has been considered one of the most promising biopolymers. Despite its biodegradability, biocompatibility and unique biological properties, gelatine exhibits poor mechanical and adhesive properties, limiting its end-use applications. The chemical modification and blending of gelatine with other biomaterials are strategies proposed to improve its bioadhesivity. Here we discuss the classical approaches involving a variety of polymer blends and composite systems containing gelatine, and gelatine modifications via thiolation, methacrylation, catechol conjugation, amination and other newly devised strategies. We highlight several of the latest studies on these strategies and their relevant findings.

Optimization of Fermentation Conditions for Carrageenase Production by Cellulophaga Species: A Comparative Study

Simple Summary

Cellulophaga species are rarely studied marine bacteria with the potential for carrageenase production. We examined the carrageenase secretion ability of six bacterial species from the Cellulophaga genus. Among them, C. algicola produced the maximum amount of ι-carrageenase. Most of the bacteria produced their highest quantity of enzymes at 25 °C after 48 h of incubation time. The maximum enzyme production was achieved with the fermentation medium composition of 30 g/L sea salt, 1.4 g/L furcellaran and 3 g/L yeast extract. In addition, the properties of the ultrafiltered ι-carrageenase extracted from C. algicola were studied.

Abstract

Carrageenases appear in various species of marine bacteria and are widely used for the degradation of carrageenans, the commercially significant sulphated polysaccharides. The carrageenase production ability of six different Cellulophaga species was identified, with ι-carrageenase being the most abundant carrageenolytic enzyme. C. algicola was the most potent strain, followed by C. fucicola and C. geojensis, whereas C. pacifica was the least effective carrageenase producer among the studied strains. The enzyme production was maximized using the one-factor-at-a-time optimization method. The optimal incubation temperature was identified as 25 °C and the incubation time was set as 48 h for all tested species. The optimal medium composition for Cellulophaga strains was determined as 30 g/L sea salt, 1.4 g/L furcellaran, and 3 g/L yeast extract. An ultrafiltered enzyme extracted from C. algicola had the highest activity at around 40 °C. The optimal pH for enzymatic degradation was determined as 7.8, and the enzyme was fairly stable at temperatures up to 40 °C.

The Role of Carrageenan in Inflammatory Bowel Diseases and Allergic Reactions: Where Do We Stand?

Carrageenan (CGN) is a high molecular weight polysaccharide extracted from red seaweeds, composed of D-galactose residues linked in β-1,4 and α-1,3 galactose-galactose bond, widely used as a food additive in processed foods for its properties as a thickener, gelling agent, emulsifier, and stabilizer. In recent years, with the spread of the Western diet (WD), its consumption has increased. Nonetheless, there is a debate on its safety. CGN is extensively used as an inflammatory and adjuvant agent in vitro and in animal experimental models for the investigation of immune processes or to assess the activity of anti-inflammatory drugs. CGN can activate the innate immune pathways of inflammation, alter the gut microbiota composition and the thickness of the mucus barrier. Clinical evidence suggests that CGN is involved in the pathogenesis and clinical management of inflammatory bowel diseases (IBD), indeed food-exclusion diets can be an effective therapy for disease remission. Moreover, specific IgE to the oligosaccharide α-Gal has been associated with allergic reactions commonly referred to as the "α-Gal syndrome". This review aims to discuss the role of carrageenan in inflammatory bowel diseases and allergic reactions following the current evidence. Furthermore, as no definitive data are available on the safety and the effects of CGN, we suggest gaps to be filled and advise to limit the human exposure to CGN by reducing the consumption of ultra-processed foods.

Clean Label Trade-Offs: A Case Study of Plain Yogurt

Consumer demand for clean label has risen in recent years. However, clean label foods with simple and minimalistic ingredient lists are often expensive to produce and/or may possess less desirable sensory qualities. Accordingly, understanding consumer preferences regarding the clean label trend would be of great interest to the food industry. Here we investigate how ingredient lists and associated sensory quality descriptions may influence consumer preferences using a hypothetical choice experiment. In particular, we test the impacts of four common stabilizers (carrageenan, corn starch, milk protein concentrate, and pectin) and textural characteristics on preferences and willingness to pay for plain yogurt. A total of 250 yogurt consumers participated in the study. The results of a mixed logit analysis suggest that clean labeling significantly increases the likelihood of consumer choice, while poor texture reduces consumer choice. More importantly, the negative impact of poor texture seems to be less significant for clean label yogurts compared to that for yogurts with longer ingredient lists. Among all stabilizers, corn starch in particular has a significant negative impact on consumer choice. The estimated average consumer willingness to pay for clean labels is between $2.54 and $3.53 for 32 oz yogurt formulations. Furthermore, clean labels minimize the negative impact of textural defects with consumers willing to pay an estimated premium of $1.61 for the family size yogurt with a simple ingredient list. Results of latent class modeling reveal two classes of consumers with similar patterns of demand who prefer clean labels and, on average, would rather purchase a yogurt with a textural defect than opt out of purchasing a yogurt entirely. Implications for the food industry are discussed.

Food-grade carrageenans and their implications in health and disease

Food additives, often used to guarantee the texture, shelf-life, taste, and appearance of processed foods, have gained widespread attention due to their increased link to the growing incidence of chronic diseases. As one of the most common additives, carrageenans have been used in human diets for hundreds of years. While classified as generally recognized as safe (GRAS) for human consumption, numerous studies since the 1980s have suggested that carrageenans, particularly those with random coil conformations, may have adverse effects on gastrointestinal health, including aggravating intestinal inflammation. While these studies have provided some evidence of adverse effects, the topic is still controversial. Some have suggested that the negative consequence of the consumption of carrageenans may be structure dependent. Furthermore, pre-existing conditions may predispose individuals to varied outcomes of carrageenan intake. In this review, structure-function relationships of various carrageenans in the context of food safety are discussed. We reviewed the molecular mechanisms by which carrageenans exert their biological effects. We summarized the findings associated with carrageenan intake in animal models and clinical trials. Moreover, we examined the interactions between carrageenans and the gut microbiome in the pathogenesis of gastrointestinal disorders. This review argues for personalized guidance on carrageenan intake based on individuals' health status. Future research efforts that aim to close the knowledge gap on the effect of low-dose and chronic carrageenan intake as well as interactions among food additives should be conducive to the improved safety profile of carrageenans in processed food products.

Immunomodulating Properties of Carrageenan from Tichocarpus crinitus

Several in vivo immunotropic effects of κ/β-carrageenan isolated from the red algae Tichocarpus crinitus were studied, by orally administering it at 100 mg/kg/day to mice for 7 days. Serum levels of IFN-γ, IL-12, IL-1β, and IL-4 were measured. Carrageenan's ability to influence development of LPS-induced inflammation was also assessed. Oral administration of κ/β-carrageenan increased serum levels of all the studied cytokines at least twice in comparison to the intact mice, while intraperitoneal LPS injection at 1 mg/kg increased concentration of only the pro-inflammatory cytokines: IFN-γ, IL-12, and IL-1β. Furthermore, κ/β-carrageenan demonstrated a higher efficacy at inducing IFN-γ production than LPS. Previous 7-day-long oral carrageenan administration impaired development of LPS-induced inflammation: level of IL-1β dropped below that found in intact mice, while IFN-γ and IL-12 concentrations were at least 40% lower than in mice with LPS-induced inflammation. Murine peritoneal macrophages were also affected by the oral administration of the κ/β-carrageenan: their motility was increased, and morphology altered. In sum, we have demonstrated that κ/β-carrageenan, when administered orally, is not only not immunologically inert, but at the dose of 100 mg/kg possesses pharmacologically exploitable effects.

Seaweed Polysaccharide Based Products and Materials: An Assessment on Their Production from a Sustainability Point of View

Among the various natural polymers, polysaccharides are one of the oldest biopolymers present on the Earth. They play a very crucial role in the survival of both animals and plants. Due to the presence of hydroxyl functional groups in most of the polysaccharides, it is easy to prepare their chemical derivatives. Several polysaccharide derivatives are widely used in a number of industrial applications. The polysaccharides such as cellulose, starch, chitosan, etc., have several applications but due to some distinguished characteristic properties, seaweed polysaccharides are preferred in a number of applications. This review covers published literature on the seaweed polysaccharides, their origin, and extraction from seaweeds, application, and chemical modification. Derivatization of the polysaccharides to impart new functionalities by chemical modification such as esterification, amidation, amination, C-N bond formation, sulphation, acetylation, phosphorylation, and graft copolymerization is discussed. The suitability of extraction of seaweed polysaccharides such as agar, carrageenan, and alginate using ionic solvent systems from a sustainability point of view and future prospects for efficient extraction and functionalization of seaweed polysaccharides is also included in this review article.

On the Health Benefits vs. Risks of Seaweeds and Their Constituents: The Curious Case of the Polymer Paradigm

To exploit the nutraceutical and biomedical potential of selected seaweed-derived polymers in an economically viable way, it is necessary to analyze and understand their quality and yield fluctuations throughout the seasons. In this study, the seasonal polysaccharide yield and respective quality were evaluated in three selected seaweeds, namely the agarophyte Gracilaria gracilis, the carrageenophyte Calliblepharis jubata (both red seaweeds) and the alginophyte Sargassum muticum (brown seaweed). It was found that the agar synthesis of G. gracilis did not significantly differ with the seasons (27.04% seaweed dry weight (DW)). In contrast, the carrageenan content in C. jubata varied seasonally, being synthesized in higher concentrations during the summer (18.73% DW). Meanwhile, the alginate synthesis of S. muticum exhibited a higher concentration (36.88% DW) during the winter. Therefore, there is a need to assess the threshold at which seaweed-derived polymers may have positive effects or negative impacts on human nutrition. Furthermore, this study highlights the three polymers, along with their known thresholds, at which they can have positive and/or negative health impacts. Such knowledge is key to recognizing the paradigm governing their successful deployment and related beneficial applications in humans.

Pilot scale isolation of exopolysaccharides from Streptococcus thermophilus DGCC7710: Impact of methodical details on macromolecular properties and technofunctionality

Exopolysaccharides (EPS) from Streptococcus thermophilus provide similar technofunctionality such as water binding, viscosity enhancing and emulsifying effects as commercial thickeners at a significant lower concentration. Despite their high technofunctional potential, hetero polysaccharides from lactic acid bacteria are still not commercially used in unfermented foods, as the small amount of synthesised EPS calls for a high isolation effort. This study aims to analyse the macromolecular properties of EPS and cell containing isolates from S. thermophilus DGCC7710 obtained by different isolation protocols, and to link these data to the technofunctionality in model food systems. The EPS content of the isolates was affected by the microfiltration/ultrafiltration membranes used for cell removal/dialysis, respectively, and was 89% at maximum. There was no link between purity of the isolates, molecular mass (3 × 106 Da) and intrinsic viscosity (0.53 - 0.59 mL/mg) of the EPS. After adding EPS containing isolates to milk, gel stiffness after acidification increased by 25% at maximum, depending on the type and concentration of the specific isolate. Partly purified, cell containing isolates were effective at low absolute EPS concentration (approx. 0.1 g/kg) and therefore represent, together with their simple isolation protocol, an interesting approach to introduce microbial EPS into non-fermented products.

Antioxidant Potential of Physicochemically Characterized Gracilaria blodgettii Sulfated Polysaccharides

Marine rhodophyte polysaccharides have a wide range of described biological properties with nontoxic characteristics, and show great potential in prebiotics and the functional foods industries. However, there is a virtual lack of Gracilaria blodgettii polysaccharides (GBP) profiling and their bioactivities. This study was designed while keeping in view the lack of physical and chemical characterization of GBP. This polysaccharide was also not previously tested for any bioactivities. A linear random coil conformation was observed for GBP, which was found to be a polysaccharide. A significant sulfate (w/w, 9.16%) and 3,6-anhydrogalactose (AHG, w/w, 17.97%) content was found in GBP. The significant difference in its setting (27.33 °C) and melting (64.33 °C) points makes it resistant to increasing heat. This, in turn, points to its utility in industrial scale processing and in enhancing the shelf-life of products under high temperatures. A radical scavenging activity of 19.80%, 25.42% and 8.80% was noted for GBP (3 mg/mL) in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azino-bis (ABTS) and hydroxyl radical (HO) scavenging assays, respectively. Therefore, the findings suggest that Gracilaria blodgettii polysaccharides display a good antioxidant potential and may have potential applications in the functional food industry.

Safety and efficacy of iota-carrageenan nasal spray in treatment and prevention of the common cold

The common cold is one of the most frequent viral infections in humans. Although benign, its symptoms result in economic burden and can lead to severe or even fatal complications in children, elderly and groups with comorbidities. The main purpose of the treatment is the relief of symptoms; however, the medication is often associated with adverse effects. Iota-carrageenan is a polysaccharide that reveals antiviral activity by binding to viruses, inhibiting its replications and, consequently, its viral propagation. This systematic review of the literature aims to compare the effectiveness of an iota-carrageenan nasal spray to placebo. This systematic review was conducted through research in Cochrane Database, PubMed, Science Direct, SpringerLink, Oxford Journals, Elsevier, ClinicalKey, Wiley Online Library, Embase databases, in order to collect randomized and controlled clinical trials. In total, the research provided four articles regarding clinical trials for comparing iota-carrageenan nasal spray with placebo. The results show it has potent antiviral activity compared to placebo and a favorable safety profile. Although further research is needed, the concept of a physical barrier capable of reducing viral penetration of epithelial cells in the nasal mucosa is appealing, and could lead to alternative approaches, with positive impact on global health.

The role of deep eutectic solvents and carrageenan in synthesizing biocompatible anisotropic metal nanoparticles

Plasmonic metal nanoparticles are widely used for many applications due to their unique optical and chemical properties. Over the past decade, anisotropic metal nanoparticles have been explored for imaging, sensing, and diagnostic applications. The variations and flexibility of tuning the size and shape of the metal nanoparticles at the nanoscale made them promising candidates for biomedical applications such as therapeutics, diagnostics, and drug delivery. However, safety and risk assessment of the nanomaterials for clinical purposes are yet to be made owing to their cytotoxicity. The toxicity concern is primarily due to the conventional synthesis route that involves surfactants as a structure-directing agent and as a capping agent for nanoparticles. Wet chemical methods employ toxic auxiliary chemicals. However, the approach yields monodispersed nanoparticles, an essential criterion for their intended application and a limitation of the green synthesis of nanoparticles using plant extracts. Several biocompatible counterparts such as polymers, lipids, and chitosan-based nanoparticles have been successfully used in the synthesis of safe nanomaterials, but there were issues regarding reproducibility and yield. Enzymatic degradation was one of the factors responsible for limiting the efficacy. Hence, it is necessary to develop a safer and nontoxic route towards synthesizing biocompatible nanomaterials while retaining morphology, high yield, and monodispersity. In this regard, deep eutectic solvents (DESs) and carrageenan as capping agent for nanoparticles can ensure the safety. Carrageenan has the potential to act as antibacterial and antiviral agent, and adds enhanced stability to the nanoparticles. This leads to a multidimensional approach for utilizing safe nanomaterials for advanced biomedical and clinical applications.

Macroalgal dietary glycans: potential source for human gut bacteria and enhancing immune system for better health

Macroalgae are the diverse group of photosynthetic algae found at the intertidal regions of oceans. Recent advances suggest that macroalgal derived glycans have tremendous potential to maintain gut microbiome and immune system. The human gut bacteria harbor unique arsenals for utilizing a variety of macroalgal glycans, and produce a variety of oligosaccharides in vivo. Those oligosaccharides interact with immune cell receptors, and also are available for microbial fermentation, thus play magnificent roles in balancing the gut homeostasis. However, this area of research is still in infancy condition in term to understand their molecular interactions. For wooing this area, we urge to emphasize more studies on mechanistic level sympathetic of depolymerizing marine dietary glycans by gut bacteria and elucidating molecular aspect of glycans to cell receptors interactions. This will invent new nutraceutical strategies to purposefully manipulate the microbial composition to improve health. Therefore, review focuses on the recent development of mechanistic understanding of human gut bacterial communities for utilizing macroalgal derived glycans. Recent trends of application of glycans in modulating immune system at mechanistic level and their available evidences are discussed.

Purification, characterization and antioxidant activity of polysaccharides from Porphyra haitanensis

In order to study the antioxidant activity of Porphyra haitanensis polysaccharides and the effect of their structure on the antioxidant activity, the Porphyra haitanensis polysaccharide (PHP), prepared by hot water extraction and alcohol precipitation, was separated and purified by Cellulose DEAE-52 ion exchange and Sephadex G-100 column chromatography. Three purified components including PHP1, PHP2 and PHP3 were obtained, and chemical composition analysis and structural characterization were performed. The in vitro free radical scavenging activity of the purified polysaccharide fractions and their ability to relieve oxidative stress in macrophage RAW264.7 were investigated. The results indicated that all the three fractions possessed appreciable DPPH radical, superoxide anion radical, and hydroxyl radical scavenging ability and reducing power. They were also found to effectively reduce the MDA content and ROS level, and to improve the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) in H₂O₂-treated RAW264.7 cells. Among the three polysaccharides, PHP3 possessed the most potent activity. Porphyra haitanensis polysaccharides have potential to develop as natural non-toxic antioxidants and may find application as the ingredients of functional foods.

An overview on red algae bioactive compounds and their pharmaceutical applications

Objectives To review red algae bioactive compounds and their pharmaceutical applications. Content Seaweed sources are becoming attractive to be used in health and therapeutics. Among these red algae is the largest group containing bioactive compounds utilized in cosmetic, pharmaceutical, food industry, manure and various supplements in food formula. Various significant bioactive compounds such as polysaccharides (aginate, agar, and carrageenan), lipids and polyphenols, steroids, glycosides, flavanoids, tannins, saponins, alkaloids, triterpenoids, antheraquinones and cardiac glycosides have been reported in red algae. The red algae have rich nutritional components Different polysaccharides of red algae possess the antiviral potential namely agarans, carrageenan, alginate, fucan, laminaran and naviculan. Sulfated polysaccharides and carraginans of red algae are rich source of soluble fibers which can account for antitumor activities depending upon chemistry of various secondary metabolites and metabolism of cell line. Flavons-3-ols containing catechins from many red algae block the telomerase activity in colon cancer cells. Contraceptive agents were tested from red algae as a source for post-coital. Lectin of red algae showed pro-healing properties and anti-ulcerogenic activities. Carragenates from red algae also conferred a positive influence on diabetes. Red algae depicted a reducing effect on plasma lipids and obesity. Porphyran from red alga can act as anti-hyperlipidemic agent also reduces the apolipoprotein B100 via suppression of lipid synthesis in human liver. Summary The polyphenolic extracts of Laurencia undulate, Melanothamnus afaqhusainii and Solieria robusta extract show anti-inflammatory effects against multiple genera of devastating fungi. Antioxidants such as phlorotannins, ascorbic acids, tocopherols, carotenoids from red algae showed toxicity on some cancer cells without side effects. Red algae Laurencia nipponica was found insecticidal against mosquito larvae. Red algae fibers are very important in laxative and purgative activities. Gracilaria tenuistipitat resisted in agricultural lands polluted with cadmium and copper. Outlook In the recent decades biotechnological applications of red algae has been increased. Polysaccharides derived from red algae are important tool for formulation of drugs delivery system via nanotechnology.

Native κ-carrageenan induced-colitis is related to host intestinal microecology

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, has gradually emerged as a public health challenge worldwide. Carrageenan is a popular food additive that has been in use for decades. However, controversy exists regarding to the safety of carrageenan due to its exacerbation of colitis in experimental models. In this study, we studied the effects of vehicle and host intestinal microflora on carrageenan inflammatory properties in C57BL/6 J mice. We found that in high-fat diet model, native carrageenan in drinking water increased the disease activity index (DAI), myeloperoxidase (MPO) activity and the mRNA expression of TLR4 in colon, whereas carrageenan-supplemented diet has no visible effects. However, no signs of colitis were observed under low-fat diet regardless of the mode of vehicle used. Moreover, we discovered that carrageenan-induced colitis in high-fat diet model was robustly correlated with changes in the composition of gut microbiota, specifically Alistipes finegoldii and Bacteroides acidifaciens. Hence, we propose that the inflammatory property of carrageenan is influenced greatly by its intake form via modification of host intestinal microecology.

Effect of Carrageenans on Vegetable Jelly in Humans with Hypercholesterolemia

Changes in lipid profile constitute the main risk factor for cardiovascular diseases. Algae extracted carrageenans are long-chain polysaccharides and their ability to form gels provides for the formation of vegetable jelly. The objective was to evaluate the bioactive potential of carrageenan (E407) in the lipid profile, after ingestion of jelly. A total of 30 volunteers of both sexes, aged 20-64 years and with total cholesterol (TC) values ≥200 mg/dL, who ingested 100 mL/day of jelly for 60 days, were studied. All had two venous blood collections: before starting the jelly intake and after 60 days. At both times, TC, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triglycerides (TG), were evaluated using commercial kits and spectrophotometer. The statistics were performed using the SPSS 25.0 software and p < 0.05 were considered statistically significant. Serum values after 60 days of jelly intake revealed a statistically significant decrease in TC levels (5.3%; p = 0.001) and LDL-C concentration (5.4%; p = 0.048) in females. The daily intake of vegetable jelly for 60 days showed a reduction in serum TC and LDL-C levels in women, allowing us to conclude that carrageenan has bioactive potential in reducing TC concentration.

Current Trends on Seaweeds: Looking at Chemical Composition, Phytopharmacology, and Cosmetic Applications

Seaweeds have received huge interest in recent years given their promising potentialities. Their antioxidant, anti-inflammatory, antitumor, hypolipemic, and anticoagulant effects are among the most renowned and studied bioactivities so far, and these effects have been increasingly associated with their content and richness in both primary and secondary metabolites. Although primary metabolites have a pivotal importance such as their content in polysaccharides (fucoidans, agars, carragenans, ulvans, alginates, and laminarin), recent data have shown that the content in some secondary metabolites largely determines the effective bioactive potential of seaweeds. Among these secondary metabolites, phenolic compounds feature prominently. The present review provides the most remarkable insights into seaweed research, specifically addressing its chemical composition, phytopharmacology, and cosmetic applications.

Physicochemical characterization and antioxidant activity of sulphated polysaccharides derived from Porphyra haitanensis

This study was designed to fully characterize Porphyra haitanensis polysaccharides, and to evaluate their antioxidant activity. The polysaccharides primarily contained galactose and 3,6-anhydrogalactose in a molar ratio of 1.2:1.0, respectively and sulfate content about 3.8%. The molecular weight of polysaccharides is 2.5 × 10⁵ Da. Scanning electron microscopy and atomic force microscopy of the polysaccharides pointed towards an irregular network with more or less hexagonal and a few rectangular pores. The chemical structure was confirmed through Fourier transform infrared spectroscopy, and 1D and 2D nuclear magnetic resonance structural characterization wherein → 4-3,6-anhydro-α-L-galactopyranose-(1 → 3)-β-D-galactopyranose segments. The extracted polysaccharides revealed relatively high 2, 2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activity (53.16% at 2 mg/mL), moderate 2,2-diphenyl-1-picrylhydrazyl radical scavenging efficacy (34.63% at 2 mg/mL), and low hydroxyl radical scavenging potential (23.80% at 2 mg/mL). Further purification of these polysaccharides, hence, is advised for their potential role as antioxidants in the food, pharmaceutical and cosmeceutical industry.

Quantitative analysis of binding affinities and characterization of β-lactoglobulin and λ-carrageenan as a function of pH

λ-Carrageenan (λcar) interacted with β-lactoglobulin (βlg) immediately to form βlg-λcar complexes when used as an additive in milk. The formation of complexes is the key process through which to explore the bioapplication of λcar, which is a complicated process and influenced by many factors. In this study, the formation process and effect of pH were ascertained by the binding affinity, hydrodynamic diameter, and secondary structure. Results showed that the interaction was spontaneously exothermic and the complexes were soluble. The binding affinities (Ka) decreased from 9.0 ± 1.3 × 10⁵ to 1.3 ± 0.8 × 10⁵  M^-1 , and the stoichiometry also decreased as the pH was increased from 4 to 7. Furthermore, DLS showed a larger hydrodynamic diameter of the complexes at lower pH. Moreover, the complexes induced a change in the secondary structural components of βlg at lower pH. PRACTICAL APPLICATIONS: The secondary structure of βlg was changed by the interaction of λcar, which resulted in βlg-λcar complexes under acidic conditions. The soluble βlg-λcar complexes showed a good stability against aggregation. Thus, they can enhance the textural properties and stability of acidic dairy drinks, and can be used to accurately formulate ingredients in the food ingredient industry.

Lambda-Carrageenan Enhances the Effects of Radiation Therapy in Cancer Treatment by Suppressing Cancer Cell Invasion and Metastasis through Racgap1 Inhibition

Radiotherapy is used extensively in cancer treatment, but radioresistance and the metastatic potential of cancer cells that survive radiation remain critical issues. There is a need for novel treatments to improve radiotherapy. Here, we evaluated the therapeutic benefit of λ-carrageenan (CGN) to enhance the efficacy of radiation treatment and investigated the underlying molecular mechanism. CGN treatment decreased viability in irradiated cancer cells and enhanced reactive oxygen species accumulation, apoptosis, and polyploid formation. Additionally, CGN suppressed radiation-induced chemoinvasion and invasive growth in 3D lrECM culture. We also screened target molecules using a gene expression microarray analysis and focused on Rac GTPase-activating protein 1 (RacGAP1). Protein expression of RacGAP1 was upregulated in several cancer cell lines after radiation, which was significantly suppressed by CGN treatment. Knockdown of RacGAP1 decreased cell viability and invasiveness after radiation. Overexpression of RacGAP1 partially rescued CGN cytotoxicity. In a mouse xenograft model, local irradiation followed by CGN treatment significantly decreased tumor growth and lung metastasis compared to either treatment alone. Taken together, these results suggest that CGN may enhance the effectiveness of radiation in cancer therapy by decreasing cancer cell viability and suppressing both radiation-induced invasive activity and distal metastasis through downregulating RacGAP1 expression.

A Pilot Study on Anti-Obesity Mechanisms of Kappaphycus Alvarezii: The Role of Native κ-Carrageenan and the Leftover Sans-Carrageenan Fraction

Kappaphycus is a commercially important edible red alga widely cultivated for carrageenan production. Here, we aimed to investigate the anti-obesity mechanism of Kappaphycus alvarezii by comparing the effects of whole seaweed (T), extracted native κ-carrageenan (CGN), and the leftover fraction sans-carrageenan (SCGN) supplementations (5%, w/w) on diet-induced obese C57BL/6J mice. A high-fat diet induced both a raised body fat percentage and serum cholesterol level, increased adipocytes size, abnormal levels of adipocytokines, and promoted gut dysbiosis. Our results showed that, overall, both CGN and SCGN were more effective in reversing obesity and related metabolic syndromes to normal levels than T. Furthermore, these findings suggested that CGN- and SCGN-modulated gut dysbiosis induced by a high-fat diet, which may play an influencing role in adiponectin dysregulation. Our data also showed some evidence that CGN and SCGN have distinct effects on selected genes involved in lipid metabolism. In conclusion, both κ-carrageenan and SCGN have novel anti-obesity potential with possible different mechanisms of action.

Oligosaccharides Derived from Red Seaweed: Production, Properties, and Potential Health and Cosmetic Applications

Because of their potential use as functional ingredients in human nutrition, oligosaccharides derived from natural sources are receiving paramount consideration. Red seaweed, a proven rich source of agar and carrageenan, is one of the most abundantly present sources of such oligosaccharides. Agaro-oligosaccharides (AOS) and carrageenan-oligosaccharides (COS) are produced from agar and carrageenan, respectively, through chemical and enzymatic hydrolyses. Enzymatic hydrolysis of agar and carrageenan into oligosaccharides is preferred in industrial production because of certain problems associated with chemical hydrolysis, including the release of high amounts of monosaccharides and undesirable toxic products, such as furfural. AOS and COS possess many biological activities, including prebiotic, immuno-modulatory, anti-oxidant, and anti-tumor activities. These activities are related to their chemical structure, molecular weight, degree of polymerization, and the flexibility of the glycosidic linkages. Therefore, the structure–function relationship and the mechanisms occurring during the specific biological applications of AOS and COS are discussed herein. Moreover, the chromatographic separation, purification, and characterization of AOS and COS are also part of this review. This piece of writing strives to create a new perspective on the potential applications of AOS and COS in the functional food and pharmaceutical industry.

The perception of aquaculture on the Swedish West Coast

Efforts are on the way on the Swedish West Coast to develop the capacity for cultivation of marine resources, notably of kelps. Given that this is a region of great natural and national heritage, public opposition to marine developments has been identified as a possible risk factor. This survey thus sought to shed light on awareness levels, perceptions of different types of aquaculture and on reactions to a scenario depicting future aquaculture developments on the West Coast. When asked about their general opinions of aquaculture, respondents tended to be favourable though a majority chose neutral responses. On the whole, respondents were favourable to the depicted scenario. Finally, it was found that the high-awareness group tended to be more supportive than the low or medium-awareness groups, hinting at the benefits of increasing awareness to reduce public aversion and to support a sustainable development of aquaculture on the Swedish West Coast.

Re-evaluation of carrageenan (E 407) and processed Eucheuma seaweed (E 407a) as food additives

The present opinion deals with the re-evaluation of the safety of food-grade carrageenan (E 407) and processes Eucheuma seaweed (E 407a) used as food additives. Because of the structural similarities, the Panel concluded that processed Eucheuma seaweed can be included in the evaluation of food-grade carrageenan. Poligeenan (average molecular weight 10-20 kDa) has not been authorised as a food additive and is not used in any food applications. In its evaluation of carrageenan (E 407) and processed Eucheuma seaweed (E 407a), the Panel noted that the ADME database was sufficient to conclude that carrageenan was not absorbed intact; in a subchronic toxicity study performed with carrageenan almost complying with the EU specification for E 407 in rats, the no-observed-adverse-effect level (NOAEL) was 3,400-3,900 mg/kg body weight (bw) per day, the highest dose tested; no adverse effects have been detected in chronic toxicity studies with carrageenan in rats up to 7,500 mg/kg bw per day, the highest dose tested; there was no concern with respect to the carcinogenicity of carrageenan; carrageenan and processed Eucheuma seaweed did not raise a concern with respect to genotoxicity; the NOAEL of sodium and calcium carrageenan for prenatal developmental dietary toxicity studies were the highest dose tested; the safety of processed Eucheuma seaweed was sufficiently covered by the toxicological evaluation of carrageenan; data were adequate for a refined exposure assessment for 41 out of 79 food categories. However, the Panel noted uncertainties as regards the chemistry, the exposure assessment and biological and toxicological data. Overall, taking into account the lack of adequate data to address these uncertainties, the Panel concluded that the existing group acceptable daily intake (ADI) for carrageenan (E 407) and processed Eucheuma seaweed (E 407a) of 75 mg/kg bw per day should be considered temporary, while the database should be improved within 5 years after publication of this opinion.